Black Rock Forest maintains eight long-term forest monitoring plots in Cornwall, NY. Four pairs of plots were established in 1931 to compare thinning treatments to nearby control plots. Four plots are approximately 0.25 acres and the other four are 0.1 acres. Tree species, diameter at breast height, height and canopy class have been measured on all stems greater than 1 inch in diameter since 1931. Plots were revisited every five years until the 1990s and annually from 1994 to 2023.